/// <summary>
/// Returns the FSHP hash of password
/// </summary>
/// <param name="password">Encoded to bytes with UTF-8.</param>
/// <param name="salt">Byte representation of salt to be used in hashing Encoded to bytes with UTF-8.</param>
/// <param name="saltlen">Length of the salt to be generated.</param>
/// <param name="rounds">Number of hashing rounds.</param>
/// <param name="variant">FSHP variant indicating the behaviour and/or hashing algorithm
/// to be used.
/// 0: SHA-1 (not recommended)
/// 1: SHA-256
/// 2: SHA-384
/// 3: SHA-512
/// </param>
/// <returns>FSHP hash of password</returns>
public static String crypt(byte[] password, byte[] salt, int saltlen, int rounds, int variant)
{
// Ensure we have sane values for salt length and rounds.
if (saltlen < 0)
saltlen = 0;
if (rounds < 1)
rounds = 1;
// if salt is null, we generate a random one.
RNGCryptoServiceProvider CryptoRng = new RNGCryptoServiceProvider();
if (salt == null) {
salt = new byte[saltlen];
CryptoRng.GetBytes(salt);
} else {
saltlen = salt.Length;
}
HashAlgorithm hash;
switch (variant) {
case 0:
hash = new SHA1Managed();
break;
case 1:
hash = new SHA256Managed();
break;
case 2:
hash = new SHA384Managed();
break;
case 3:
hash = new SHA512Managed();
break;
default:
throw new Exception();
}
hash.Initialize();
byte[] saltedPassword = new byte[salt.Length + password.Length];
salt.CopyTo(saltedPassword, 0);
password.CopyTo(saltedPassword, salt.Length);
// Round 1
byte[] hashBytes = hash.ComputeHash(saltedPassword);
// ...and other rounds.
for (int i = 1; i < rounds; i++) {
hashBytes = hash.ComputeHash(hashBytes);
}
string meta = "{FSHP" + variant + "|" + saltlen + "|" + rounds +"}";
byte[] saltdigest = new byte[salt.Length + hashBytes.Length];
salt.CopyTo(saltdigest, 0);
hashBytes.CopyTo(saltdigest, salt.Length);
string b64saltdigest = Convert.ToBase64String(saltdigest);
return meta + b64saltdigest;
}
